The present embodiment relates generally to the production of water treatment compositions for the clarification of bodies of water by removal of dissolved solids, dissolved organic materials (i.e. natural pigments and humic acids) and other anions such as fluoride and chloride as well as the removal of total phosphorus from such bodies of water. More particularly, the compositions are designed to be delivered to concentrated or impounded total phosphorus located at the bottom of various bodies of water and may be produced in a variety of physical forms that are designed to enhance the delivery of the compositions to a desired location in a body of water such as pellets, tablets and extruded noodles, briquettes or ribbons. The compositions include alum and a smectite mineral-bearing industrial material such as bentonite (montmorillonite), attapulgite, saponite, hectorite, sepiolite and fullers earth. The compositions optionally include one or more of a buffer and algaecide coatings or additives. The compositions can be delivered to a wide range of locations in bodies of water including the “sediment water interface” which is an area that can be generally defined as the top six inches of sediment combined with the deepest six inches of water. Even more particularly, the compositions are designed so that when they are dropped through a body of water, the alum is released when the pellet reaches a desired location in the water, thereby treating the phosphorus more efficiently and using or consuming less alum.
Acidic metal salt and sulfate solutions, such as aluminum sulfate ((Al2SO4)3·14H2O) solutions, commonly known and referred to as “alum,” have long been used to remove color and suspended particles, as well as organic and microbiological contaminants from water. Alum is readily available and when diluted with surface water, it can function as a coagulant, flocculent, precipitant and emulsion breaker. As a coagulant, alum removes the primary nutrient for blue-green algae in the water. This function is important because these algae remove oxygen from the water (known as biochemical oxygen demand or BOD) and thus pose a danger to fish. Alum also forms an insoluble precipitate or floccule, i.e., a floc, with the impurities in the water. The floc grows in size as it attracts suspended and colloidal particles and organic compounds present in the water. The floc settles out of the water over time and can be removed by techniques that are well known to those skilled in the art such as by decanting or filtration.
One of the most difficult problems in water pollution control is the growth of algae. As noted above, algal organisms exert a BOD on the water and the algal BOD can often exceed the oxygen resources of the water. Algal growths can also cause unpleasant tastes and odors in water supplies. Dissolved phosphorus provide algae with a necessary nutrient supply. If the phosphorus supply could be removed the algae would not survive or flourish in the water column and a water pollution control problem would be addressed. An additional difficulty associated with the treatment of phosphorus in water is that the majority of the phosphorus (50–90%) is concentrated at the sediment-water interface of an impoundment and current application techniques involving alum primarily treat the phosphorus closer to the surface of the body of water. In addition, current techniques have been focused on nearly instantaneous sorption of phosphorus. As a result, the body of existing products and techniques do not perform as effectively in a number of water systems, especially high energy and deep systems, and in systems that require more than just instantaneous phosphorus sorption. In the former case, alum is flushed from the target waters before it can perform. In the latter case, the alum is poorly utilized in application. Also, the alum can leave an unwanted white cloud in the water for an extended period of time.
Therefore, there is a need for simple compositions, forms and methods for treating phosphorus impoundments in bodies of water.